uPVC WINDOW - WATER TIGHTNESS
uPVC WINDOW - WATER TIGHTNESS Due to the obvious nature of its name, this property of windows appears to be the easiest to explain. Some readers might already know that windows cannot be divided into water-tight and non-water-tight. There are as many as 10 water-tightness classes defined for uncovered windows, from 1A to 9A, as well as a special class, Exxxx where the xxxx stands for the value of pressure greater than 600 Pa. Uncovered windows The term “uncovered window” is defined as any window installed in a building wall whose entire surface is exposed to weather conditions, to include wind and rain. Depending on the test pressure level and the time for which the tested window remains completely water-tight to rainwater, windows are given appropriate designations. Consequently, in reality, the “water-tightness”, also referred to as “driving-rain resistance”, of a uPVC window identifies the wind load during rainfall at which rainwater will start penetrating the interior o...